TITLE: GCN CIRCULAR NUMBER: 18346 SUBJECT: LIGO/Virgo G184098: Swift follow-up observations DATE: 15/09/20 02:16:31 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.A. Kennea (PSU), Scott Barthelmy (NASA/GSFC), Dave Burrows (PSU), Sergio Campana (INAF-OAB), Brad Cenko (NASA/GSFC), Neil Gehrels (NASA/GSFC), Paolo Giommi (ASI), Frank Marshall (NASA/GSFC), John Nousek (PSU), Paul O'Brien (U. Leicester), Julian Osborne (U. Leicester), David Palmer (LANL), Matteo Perri (ASDC), Judy Racusin (NASA/GSFC), Mike Siegel (PSU), Gianpiero Tagliaferri (INAF-OAB) report on behalf of the Swift team: Swift has performed further observations of the error region of advanced LIGO trigger G184098. The previously-reported observations covered 8 galaxies within the error region, listed below; the typical upper limit from these observations is 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV). Subsequently a 37-point tiled observation has been performed, covering a portion of the LMC within the GW error region, centred on RA,Dec = 103.8877, -68.3023 (06h 55m 33.04s, -68d 18' 08.3"), with ~60 s exposure per tile. No X-ray sources were found in these observations. The upper limits from these observations range from 3.3e-12 to 1.3e-11 erg cm^-2 s^-1 (0.3-10 keV). The galaxies covered by the original observations were: ESO089-015 ESO089-016 ESO088-018 ESO088-017 PGC298845 ESO126-002 ESO126-004 ESO089-009 ESO090-011 PGC314417 Details of these observations have been uploaded to the GraceDB. This circular is an official product of the Swift team. [GCN OPS NOTE(19sep15): This Circular was originally published on 14:01 19-Sep-2015 UT.]